JPH0381568A - Apparatus for detecting failure in ignition device of internal combustion engine - Google Patents

Abstract

PURPOSE:To perform advanced failure detection compared with simple detection of existence of failure by providing an determining and processing means for detecting operation of an internal combustion engine, identifying a part of failure detected by a failure detecting means according the operation or invalidating the failure detected by the failure detecting means. CONSTITUTION:Secondary high voltage of an ignition coil 11 is taken as a signal by a differential capacitor 21 (differential circuit), the signal is differentiated, and failure is identified by a comparison circuit 22 (failure detecting means) if the differentiated value is a specific value or less. Further operation of an internal combustion engine is sensed by an MCU 5 (determining and processing means) so that if an ignition plug confirming signal is not output per specific cylinder at the time of light load (when mixture pressure is low), high tension cord removal or breakage is identified while if the ignition plug confirming signal is not output per specific cylinder at the time of high load, abnormal wearing of the ignition plug is identified. Further, if the ignition plug confirming signal is not output with unspecific frequency, no failure is identified to prevent erroneous detection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an abnormality detection device in an ignition device for an internal combustion mPA.

[Prior Art] As an abnormality detection device in an ignition system of an internal combustion engine, for example, Japanese Patent Application Laid-Open No. 49-57231 discloses a device that monitors a voltage signal of a high voltage section on the secondary side of an ignition coil via a differentiating circuit. If the value is greater than or equal to a predetermined value, it is determined that ignition has occurred. Furthermore, in Japanese Patent Laid-Open No. 50-5735, the differential circuit described above monitors flying sparks, and a circuit that monitors the primary voltage and compares the outputs of both to determine whether there is a spark error is operated. A lamp is displayed when there is no spark.

[Problems to be Solved by the Invention] However, these devices merely detect the presence or absence of an abnormality, and the details of the abnormality cannot be known.

The purpose of this invention is not only to detect the presence or absence of an abnormality, but also to
An object of the present invention is to provide an abnormality detection device capable of performing more advanced abnormality detection.

[Means for Solving the Problems 1] The present invention includes a differentiating circuit that extracts a high voltage on the secondary side of an ignition coil as a signal and differentiates the signal, and detects an abnormality when the differential value by the differentiating circuit is less than a predetermined value. an abnormality detection means that detects the operating state of the internal combustion engine and identifies the location of the abnormality detected by the abnormality detection means according to the operating state, or an abnormality detected by the abnormality detection means; Abnormality detection in an ignition system of an internal combustion engine equipped with a determination processing means for disabling the
The gist is i@.

[Operation] The abnormality detection means determines that there is an abnormality when the differential value by the differential circuit is less than a predetermined value, and the determination processing means detects the operating state of the internal combustion engine, and the abnormality detection means detects the abnormality according to the operating state. The location of the detected abnormality is specified, or the abnormality detected by the abnormality detection means is invalidated.

[Actual Flow Example] An embodiment embodying the present invention will be described below with reference to the drawings.

FIG. 2 is an overall block diagram of the ignition system for the internal combustion engine of this embodiment. The device includes an electronic control unit (hereinafter referred to as ECU) 1, an ignition circuit 2, a high-pressure distributor 3, and a spark plug 4. Then, the ECU1 transmits an ignition signal to the ignition circuit 2, and the ignition circuit 2 outputs a high voltage to the high voltage distributor 3 based on the ignition signal. The high voltage distributor 3 is a high voltage generated in the ignition circuit 2 by a rotor brush provided on a shaft that rotates in synchronization with a camshaft or the like of an internal combustion engine (not shown) and side electrodes arranged at appropriate angular positions on the inner circumference of the rotor brush. is distributed to spark plugs 4 arranged for each cylinder.

FIG. 1 shows a specific electric circuit of the ECU1 and the ignition circuit 2. The ECU1 has a built-in micro-compact processing unit (hereinafter referred to as MCU) 5 as a determination processing means, and the MCU 3 is configured to input signals indicating the operating states of various internal combustion engines (not shown). Signals indicating this operating state include signals from an intake pressure sensor, an intake air amount sensor, an engine coolant temperature sensor, a starter drive signal, and the like. And M.C.
U3 calculates the optimum energization time and ignition timing based on the information, and outputs an ignition signal. The signal line is connected via an output buffer circuit 6 and a transistor 7 to the base terminal of a receiving transistor 8 of the ignition circuit 2. The input side of the buffer circuit 9 of the ignition circuit 2 is connected to the collector terminal of the receiving side transistor 8, and the output side of the buffer circuit 9 is connected to the base terminal of the power transistor 10. This power transistor 10 is formed by connecting two transistors 10a and 10b in a Darlington connection. Furthermore, a primary coil of an ignition coil 11 is connected to the collector terminal of the power transistor 10.

As a result, upon ignition, the waveform at each point becomes as shown in FIG. That is, the ignition signal (the potential at the emitter terminal (8 points) of the transistor 7) calculated by the MCU 3 is at a high level during energization, and has information that the falling edge of the trailing edge is the ignition timing. Upon receiving the ignition signal, the collector terminal voltage (potential at point b) of the receiving transistor 8 of the ignition circuit 2 has the same phase as the ignition signal.Then, the same phase signal amplified by the buffer circuit 9 is applied to the power transistor 10. The ignition signal supplied to the base is conductive while the ignition signal is at the high level, and the primary current flows through the ignition coil 11. When the ignition signal changes from high to low level, the primary current is cut off.

At this time, a back electromotive force is generated in the ignition coil 11,
A collector terminal (0 point) of the power transistor 10 generates a high voltage signal. This high voltage signal is converted into a high voltage for ignition of several tens of KV according to the turns ratio of the ignition coil 11 to the secondary coil, and is supplied to the high voltage distributor 3 (0
potential at a point).

As a result, sparks fly at the spark plugs 4 in each cylinder.

Furthermore, the ignition device of such an internal combustion engine is equipped with an abnormality detection device. To explain this configuration, in FIG. 1, the collector terminal of a power transistor 10 is connected to a pulse generator 12, and this pulse generator 12 monitors the primary voltage (potential at point 0) of the ignition coil 11, and When the voltage value is larger than a predetermined value, a pulse signal is output.This pulse generator 12 is connected to the base terminal of a transistor 13, and the transistor 13 is driven by the pulse signal output from the pulse generator 12.

The collector terminal of the transistor 13 of the ignition circuit 2 is connected to the ECU.
It is connected to the latch port YIGf of the MCU 3 via the buffer circuit 14 of 1. And transistor 13
The buffer circuit 14 in the ECU 1 is operated by the drive of the ignition circuit 1, and an ignition circuit operation confirmation signal (hereinafter referred to as ignition confirmation signal) is transmitted to the MCU 3.
- The buffer circuit 14 between the transistor 13 and the latch port YIGf of the MCU 3 is provided with a CR open circuit and a NOT circuit 17 consisting of a resistor 15 and a capacitor 16.

Further, the output terminal of the buffer circuit 9 of the ignition circuit 2 is connected to the set terminal of a latch circuit 18 consisting of an R-S flip-flop. Furthermore, a resistor 19.20 is connected in series to the secondary side (high voltage side) of the ignition coil 11, and a differential capacitor 21 as a differential circuit is connected to the intermediate point.
is connected. The secondary voltage of the ignition coil 11 (voltage at point e) is differentiated by the differential capacitor 21.

The comparator circuit 22 as an abnormality detection means consists of an operational amplifier 23 and two resistors 24.25.A differential capacitor 21 is connected to the non-inverting input terminal of the operational amplifier 23, and a resistor 24.25 is connected to the inverting input terminal of the operational amplifier 23. A voltage divided by is applied. Furthermore, operational amplifier 23
The output terminal of is connected to the reset terminal of the latch circuit 18.

Then, the comparison circuit 22 detects a sudden voltage change when the spark plug 4 sparks, and the latch circuit 18 is reset by the voltage detection.

The output terminal of the latch circuit 18 is the buffer 7 circuit 1 of ECU1.
4 to the input port t-YIGP of MCLJ5. Then, the MCU 3 determines the output level of the latch circuit 18 via the buffer 7 circuit 14. Incidentally, a CR open circuit and a NOT circuit 26 consisting of a resistor 24 and a capacitor 25 are provided in the buffer circuit 14 between the latch circuit 18 and the input port YIGP of the MCLI 5.

Further, in FIG. 1, a pull-up resistor 27 and a pull-down resistor 28 are used to obtain an initial state when the power is turned on, and resistors 29, 30, . The diodes 31 and 32 and the capacitor 33 are a protection circuit for removing surges from the transistor 8, and the resistor 34 and the capacitor 35 are a protection circuit for removing surges from the transistor 13.

Next, the operation of the abnormality detection device configured as described above will be explained.

FIG. 4 shows region A at the secondary voltage (potential at point e) of the ignition coil 11 in FIG. 3.

An enlarged view of B and the potential on the output side (0 point) of the differential capacitor 21 are shown. Note that the time axis in FIG. 4 is expanded compared to FIG. 3.

Since the collector terminal voltage (potential at point 0) of the power transistor 10 is connected to the trigger terminal of the pulse generator 12, when the voltage exceeds a predetermined voltage, the pulse generator 1
A pulse is output from the second output terminal (point d). This pulse serves as an ignition confirmation signal to latch port YI of MCU3.
Sent to Gf.

10- After transmitting the ignition signal, the MCU 5 checks the latch port YIGf before transmitting the next ignition signal, and if there is an input, it can be determined that the ignition circuit 2 is normal. Then, the MCU 3 checks the latch port YIGf and then clears the latch port YIGf, thereby enabling the MCU 3 to monitor the ignition circuit 2 for each ignition. At this time, M
When an abnormality occurs in the power transistor 10 or the ignition coil 11 and switching of the primary current becomes impossible, the CU 5 no longer generates an ignition confirmation signal, making it possible to detect a failure in the ignition circuit 2.

Furthermore, if the failure condition continues for a predetermined time or a predetermined number of ignitions, the MCU 3 records the occurrence of the abnormality in the abnormality storage RA.
It is designed to be stored in M.

The specific operations of these MCtJ5 will be explained with reference to the flowchart of FIG. 5. Step 100 is a module name "MIG f
m'', execution starts at the timing immediately before outputting the ignition signal in the entire program.

The MCU 3 checks in step 101 whether the latch port YIGf, which is latched by the rising edge of the ignition confirmation signal, is set to "1", and if it is set to "1", that is, the ignition confirmation signal is If it has occurred, the fail counter C of the ignition confirmation signal is set in step 102.
Clear FIGF (-〇). Furthermore, when the latch port YIGf is "0" in step 101, the MCU 3 sets the fail counter CFIGF to "1" in step 103.
” increment.

After the processing in steps 102 and 103, the MCU 3 checks in step 104 whether or not the fail counter CFIGF is larger than a predetermined value A, and if it is larger, the process proceeds to step 1.
Set the failure display flag XFIGF to "1" at 05,
After that, in step 106, the fault memory flag XBFIGF is
Set to "1". Here, the failure display flag XFI
When GF is [1], the MCU 3 lights up a fault lamp (not shown) in another routine, and also sets the fault memory flag XBF.
When IGF is "1", the content that there is an abnormality continues to be stored as long as the power supply is connected.

The MCU 3 detects the fail counter C in step 104.
If FIGF is smaller than the predetermined value A, the failure display flag XF IGF is cleared (-0) in step 107. M
After the processing in steps 106 and 107, the CU 3 resets the latch port YIGf (=O) in step 108 in preparation for inputting the next ignition confirmation signal.

Through such processing, the ignition confirmation signal is checked for each ignition, and if there is no input for a predetermined number of consecutive ignitions, the ignition confirmation signal system (operation system of the ignition circuit 2) is stored as abnormal.

Also, when the ignition circuit 2 is operating normally, the secondary high voltage of the ignition coil 11 applied to the ignition plug 4 is applied to the differential capacitor 2.1. As shown in part A of the figure, a large voltage is generated at the terminal of the differential capacitor 21 (point h) where the high voltage suddenly changes.The magnitude of this differential voltage is compared with a predetermined voltage in the comparator circuit 22, and if it is sufficiently large. A rising signal is output from the output terminal (point f) of the comparator circuit 22, and
This signal resets the latch circuit 18. This latch circuit 18 is activated at the rising edge of the ignition signal (start of energization).
Since the output terminal (point 0) of the latch circuit 18 outputs a signal substantially synchronized with the ignition signal. This signal is sent to the MCU 3 as a spark plug operation confirmation signal (hereinafter referred to as a spark plug confirmation signal). Therefore, MCU3
The signal level is checked immediately before outputting the ignition signal to start energizing, and if it is low level, it is possible to determine that the operating system of the ignition plug 4 is normal.

At this time, if the high tension cord connecting the high voltage distributor 3 to the ignition plug 4 is disconnected or if the electrode of the ignition plug 4 is abnormally worn and the gap has widened, sparks will not be able to fly only in a specific cylinder, and the third As shown in part 8 of the figure, it becomes an open waveform. Therefore, as shown in FIG. 4, the differential waveform (potential at point h) by the differential capacitor 21 changes gradually, and the comparator circuit 22 no longer generates a reset pulse. As a result, when the MCU 3 checks the input port YIGP before starting the energization process, the 13- signal level at point 0 is at a high level, making it possible to detect an abnormality in the ignition plug system.

Detection of an abnormality in the spark plug system by the MCU 3 will be explained with reference to FIG.

Step 109 is the module name "MIGVm" for checking the spark plug Mr R11 part.
module.

First, in step 110, the MCU 3 reads out the data of the next cylinder of the internal combustion engine (counter CCY CL, abnormality occurrence frequency counter CFIGP, continuous abnormality occurrence counter CFIGP2, etc.), and also reads the counter CCY CL.
After incrementing by "1", processing in each cylinder is started. Here, the counter CCYCL, the abnormality occurrence frequency counter CFIGP, and the continuous abnormality occurrence counter CFIGP2 are prepared in advance for each cylinder.

In step 111, the MCU 3 checks whether the input port YIGP, which is latched by the rising edge of the spark plug confirmation signal (potential at 0 point), is hit to "1".

If the MCU 3 is set to "1" 4-, that is, if the ignition plug confirmation signal is generated, the continuous abnormality occurrence counter CF is set in step 112.
IGP2 is decremented and guarded so that it does not become negative. Further, when the input port YIGP is rOJ in step 111, the MCU 3 increments the abnormality occurrence frequency counter CFIGP by "1" and increments the continuous abnormality occurrence counter CFIGP2 by "1" in step 113.

Here, the continuous abnormality occurrence counter CFIGP2 counts the abnormalities that occur continuously, and the abnormality occurrence frequency counter CFIGP counts how many times the abnormality occurs during a predetermined number of ignitions.

Next, in step 114, the MCU 3 checks whether the counter CCYCL for each cylinder number is greater than or equal to a predetermined value C.
If it is below, the process moves to step 124. When the counter CCYCL is equal to or higher than C in step 114, the MCU 3 sets the counter CCYCL to the initial value (=O) in step 115, and further sets the port data YSTA indicating the input state of the starter to "1" in step 116, that is, Check if starter is on.

If the starter is turned on in step 116, the MCU 3 checks in step 117 whether the continuous abnormality occurrence counter CFIGP2 is greater than or equal to a predetermined value (=D>, and if it is less than or equal to D, the process proceeds to step 123. That is, the ignition plug Mc If the starter is on and no abnormality occurs continuously while there is no input of the ignition signal, it is determined that there is no abnormality.In other words, when the ignition plug confirmation signal is not input at an unspecified period during a cold start, it is determined that there is no abnormality. If there is no output, the voltage required to cause a spark to fly (required voltage) is high when it is cold, and the vaporization of the fuel is poor, so droplets of fuel may adhere to the spark plug electrode and cause no spark to fly. It is not determined to be abnormal.

When the starter is not turned on in step 116, and in step 117, the MCU 3 sets the continuous abnormality occurrence counter CFTG.
If P2 is greater than or equal to a predetermined value, it is determined in step 118 whether the abnormality occurrence frequency counter CFIGP is greater than a predetermined value E, and if it is less than E, the process proceeds to step 123. That is, if the number of times the ignition plug confirmation signal is not input during the predetermined number of ignitions C is less than or equal to E, it is determined that there is no failure.

In step 118, the MCU3 sets the abnormality occurrence frequency counter CF.
When IGP is greater than E, in step 119 it is determined whether the load size and OAD determined by the intake air volume sensor or intake pressure sensor are greater than or equal to a predetermined value (for example, 70% of the maximum intake air volume per cycle). Determine.MCU3
When the load LOAD is less than E, the high tension code abnormal storage flag XBFIGHC is set (=1) L in step 120, and the process proceeds to step 123.

That is, if the state in which the ignition plug confirmation signal is not input during the predetermined number of ignitions C is equal to or higher than E and the load is light, the high tension code group determines that a wire breakage has occurred,
Memorize its contents.

This is because, according to Paschen's law, the voltage required to cause the spark plug 4 to fly (required voltage) increases as the pressure of the air-fuel mixture in the spark ring increases.

17- Therefore, if there is no spark plug confirmation signal for each specific cylinder during light load (when the mixture pressure is low), even though the required voltage is low,
If sparks cannot fly, it is assumed that the high tension cord is connected or that a disconnection has occurred.

Also, when the load LOAD is 1 or more in step 119, the MCU 3 checks whether the high tension code abnormal memory flag In step 122, the abnormal memory flag XBFIG of the ignition plug 4 is set.
Set PL (-1>. In other words, if the state in which there is no ignition confirmation signal during the predetermined number of ignitions C is E or higher, the state is in a high load state, and there is no memory of the high tension code abnormality) It is determined that the ignition plug 4 is abnormally worn, and the abnormal state is stored.In other words, when the gap between the ignition plug electrodes widens according to Paschen's law, the ignition plug 4
Since the voltage required to cause a spark to fly (required voltage) increases and it becomes difficult for a spark to fly under high load (when the mixture pressure is high), it is determined that the electrode of the spark plug 4 is abnormally worn.

18- Note that even if there is no ignition plug confirmation signal for each specific cylinder during cold start, it may be determined that the electrode of the ignition plug 4 is abnormally worn.

In step 123, the MCU 3 sets the abnormality occurrence frequency counter CFIGP and the continuous abnormality occurrence counter CFI of the spark plug confirmation signal.
GP2 is set to the initial value rOJ, and in step 124, the input port YIGP of the spark plug confirmation signal is reset (=O
)do.

And the high tension code abnormal memory flag XBF
If IGHC is set (-1>), the MCU 3 lights up a high tension code abnormality lamp (not shown) in another routine. Also, the abnormality memory flag XB of the ignition plug 4
If F IGPL is set (=1>), MCU3
is designed to light up an ignition plug abnormality lamp (not shown) in another routine.

In this way, in this embodiment, the high voltage on the primary side of the ignition coil 11 is extracted as a signal by the differential capacitor 21 (differential circuit), and the signal is differentiated.
2 (abnormality detection means) determines that there is an abnormality when the differential value is less than a predetermined value, and further, the MCU 5 (determination processing means) detects the operating state of the internal combustion engine, and depending on the operating state, the comparison circuit The location of the abnormality detected by the comparison circuit 22 is identified and the abnormality detected by the comparison circuit 22 is invalidated. In other words, when the load is light (when the mixing pressure is low)
If the ignition plug confirmation signal is not output for each specific cylinder, it is determined that the high tension cord is disconnected or the wire is disconnected.If the ignition plug confirmation signal is not output for each specific cylinder during high load, it is determined that the ignition plug 4 is abnormally worn. Further, when the ignition plug'MI recognition signal is not output at an unspecified period during a cold start, it is determined that there is no abnormality, thereby preventing erroneous detection.

As a result, the conventional device merely detects the presence or absence of an abnormality, and does not know the details, but the abnormality detection device of this embodiment not only detects the presence or absence of an abnormality, but also detects the presence or absence of an abnormality. It becomes possible to perform abnormality detection.

Note that this invention is not limited to the above embodiments,
For example, the next-side voltage of the ignition coil 11 can be taken out directly via the resistor 19, 20, or by
A coil may be provided around the outer periphery of the high-tension cord, and the coil may be obtained by induction. Further, the determination level of the differential voltage for flying sparks may be set to a value that can determine not only an open state but also a leak caused by smoldering due to soot.

Furthermore, although the above embodiment uses a mechanical high voltage distribution system, a low voltage distribution system including a plurality of ignition circuits can be used for similar determination.

[Effects of the Invention] As described in detail above, the present invention exhibits an excellent effect that is not limited to simply detecting the presence or absence of an abnormality, but also enables more sophisticated abnormality detection.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the electrical configuration of an abnormality detection device in an ignition system for an internal combustion engine according to an embodiment, Fig. 2 is a block diagram of an ignition system for an internal combustion engine, Fig. 3 is a diagram showing various signals, and Fig. 4 5 is a diagram showing various signals, and FIG. 5 is a flowchart for explaining the operation. Reference numeral 5 denotes an MCU as a determination processing means, 11 an Ib-21=Nition coil, 21 a differential capacitor as a differential circuit, and 22 a comparison circuit as an abnormality detection means.

Claims (1)

[Claims] 1. A differentiation circuit that extracts the high voltage on the secondary side of the ignition coil as a signal and differentiates the signal; and an abnormality detection means that determines that there is an abnormality when the differential value obtained by the differentiation circuit is less than or equal to a predetermined value; determination processing means for detecting the operating state of the internal combustion engine and identifying the location of the abnormality detected by the abnormality detecting means or invalidating the abnormality detected by the abnormality detecting means according to the operating state; 1. An abnormality detection device in an ignition system of an internal combustion engine, characterized in that: